The long range goal of this research is to elucidate mechanisms by which gonadotropins (LH and FSH) and prostaglandins (PG) influence functions of ovarian follicles and corpora lutea (CL). Emphasis is placed on a recently described LH- and hCG-induced desensitization of adenylyl cyclase in follicles and CL to LH stimulation. Adenylyl cyclase from other tissues will be used as model systems when necessary. Studies on the physiology of the ovarian adenylyl cyclases will center on: a. development of hormonal responsiveness and hormonal control of desensitization by hCG in pregnant and pseudopregnant rats and rabbits; b. hormonal control of induction of LH response in rat follicles; c. role of cAMP mediating the desensitizing effect of hCG and HL; d. effect of LH on intrafollicular cAMP and cGMP and relation to its desensitizing effect; and e. possibility that the PG-synthesizing action triggered by LH in rabbit follicles is mediated by a receptor distinct from that mediating adenylyl cyclase stimulation. Adenylyl cyclase will be determined after dissection and homogenization of the structures involved. Levels of reproductive hormones (estrogens, progestin, LH, FSH and PRL) will be determined to allow for meaningful interpretation of the data.